docs: Update docs how to serve with in memory database
docs: Update docs how to serve with in memory database

Signed-off-by: Shota SAWADA <7786ebb0431f46bdb61b18b6b75ea6230042a307@gmail.com>

ory-am/go-iam,ory/hydra,ory/hydra,ory-am/go-iam,ory-am/hydra,ory/hydra,ory/hydra